Quantitative tibial ultrasonometry versus radiographic phalangeal absorptiometry in a Caucasian pediatric population

Can ultrasound be used to estimate bone mineral density in children with growth problems?

AIM

To assess predictability of bone mineral density (BMD) of the lumbar spine (LS) determined by dual-energy x-ray absorptiometry (DXA) using by ultrasound speed of sound of the right and left radii (SOS-R and SOS-L) in patients with growth problems.

METHODS

Ultrasound and DXA were compared in patients with advanced, normal and delayed bone ages assessed by Greulich and Pyle (GP) and Tanner and Whitehouse (TW3) methods.

RESULTS

There was a strong correlation (r), of raw scores, between SOS-R and SOS-L, r = 0.81, p = 0.000 and their respective Z-scores, r = 0.78, p = 0.000. Z-score correlations were poor between SOS-R or SOS-L and LS-BMD. Sensitivity, specificity, positive and negative predictive values of SOS-R and Z-scores for predicting normal (>-1 to <1) and low (<-1) LS-BMD were poor. For high (>1) LS-BMD, Z-scores were 22%, 93%, 29% and 90%, respectively, for SOS-R and for SOS-L, 25%, 89%, 20% and 91%. For very low (<-2) LS-BMD, SOS-R and SOS-L were the same, respectively, 29%, 91%, 40% and 86%.

CONCLUSION

Ultrasound of the radius is a poor predictor of radiologically assessed BMD at the LS, especially with delayed bone age.

Evidence-based review of bone strength in children and youth with cerebral palsy

Children with cerebral palsy have various risk factors for compromised bone health. Evidence concerning their bone fragility is gathering; however, there is no consensus regarding risk factors, indications for evaluation, follow-up, or treatment. We performed an evidence-based review targeted to address the following questions concerning children with cerebral palsy: Is bone strength impaired and what are the risk factors? Are these children at increased risk for bone fractures? What are the relations between bone mineral density and fracture risk? What methods can be used for bone health assessment? How can bone strength be improved? Currently, the most acceptable method for evaluating bone status in children is dual-energy x-ray absorptiometry. Evidence demonstrates reduced bone mass in children with cerebral palsy; yet, no clear association with fractures. Preventive methods are suggested.

The bare bones of race

In this paper I examine claims of racial difference in bone density and find that the use and definitions of race in medicine lack a theoretical foundation. My central argument is that the social produces the biological in a system of constant feedback between body and social experience. By providing a different angle of vision on claimed racial differences I hope to move the conversation away from an ultimately futile discussion of nature versus nurture, where time is held constant and place seen as irrelevant, and begin to build a new paradigm for examining the contributions of geographic ancestry, individual lifecycle experience, race, and gender to varied patterns of health and disease.

Vitamin D receptor polymorphism among rickets children in Mongolia

BACKGROUND

It was reported that 32% of children under five years old in Mongolia had symptoms of rickets. Vitamin D receptor (VDR) gene polymorphism has received attention in relation to bone metabolism. We therefore investigated whether VDR polymorphism is related to high prevalence of rickets in Mongolia and to bone properties in childhood.

METHODS

We conducted a case-control study in Ulaanbaatar involving 80 children aged 7-10 years with a history of rickets (cases) and 72 children with no history of rickets (controls). VDR polymorphism was assessed using BsmI, ApaI, and TaqI, and bone properties were determined by measuring age-standardized midtibial cortical speed of sound (TCSOS).

FINDINGS

Each allelic frequency was verified to satisfy the Hardy-Weinberg equilibrium in cases, controls, and the total sample. The VDR polymorphisms among cases (BB 3%, Bb 18%, bb 80%; AA 15%, Aa 38%, aa 47%; and TT 81 %, Tt 17%, tt 3%) did not differ significantly from those among controls (BB 1%, Bb 13%, bb 86%; AA 16%, Aa 46%, aa 38%; and TT 86%, Tt 13%, tt 1%). There were no significant differences in TCSOS according to the VDR genotype among either cases or controls.

CONCLUSIONS

The VDR polymorphism does not play a major role in the development of rickets in Mongolia and has no effect on TCSOS in childhood.

Monitoring bone mass, bone density and bone geometry in children and adolescents

The number of articles dealing with pediatric bone mass measurements has flourished during the last decade. The reasons include the awareness that bone gained early in life is an important factor in determining the risk of osteoporosis later in life and the expanding number of pediatric diseases associated with low bone mass. Dual-energy x-ray absorptiometry is the most common method for measurement of bone mineral content or bone mineral density. Quantitative computed tomography and quantitative ultrasound are the emerging techniques which offer the possibility of measuring bone mineral content, bone mineral density and quantitative ultrasound parameters that are unique to children and will be discussed in this review. The interpretation of bone mass measurements is also often difficult in growing individuals and the peculiar aspects pertaining to this problem are examined.

Different diagnostic techniques for the assessment of cortical bone on osteoporotic animals

The aim of this study was to assess the capability of ultrasonography and densitometry to predict the mechanical competence of cortical bone in healthy and osteopenic rats, respectively. Thirty 10-month-old Sprague-Dawley retired breeder female rats were used and randomized into three groups of 10 animals each. A group underwent bilateral ovariectomy by dorsal approach (Ovx), another group underwent a simulated ovariectomy (Sham-Ovx), and the last group served as a sham-aged control group (Control). Sixteen weeks after surgery, the animals were euthanized and the femurs of each rat excised for ultrasonographic and densitometric measurements, and mechanical analyses. The Ovx Group had a significantly decreased amplitude dependent speed of sound (AD-SoS-about 7-8%) when compared to the other groups (p<0.0005). For Ovx animals compared with Sham-Ovx and Control rats, significant decreases in densitometric data were observed (6-13%), as well as significant decreases in femoral Max. Load (about 18%) and flexural rigidity (about 30%). The best correlation (R2=0.55, p<0.0005) found was between SoS and femoral shaft bone mineral density (SBMD). The regression coefficient R2 increased when power-law fits were used, particularly from 0.34 (p<0.001) to 0.36 (p<0.0005) in the correlation between SoS and Max. Load and from 0.21 (p<0.05) to 0.25 (p<0.01) in the correlation between SBMD and Max. Load. The ability of QUS or DXA to accurately predict the actual mechanical characteristics of bone, and in particular bone elasticity, remained relatively poor and the improvement of the power-law model did not describe exhaustively the relationships between the variables tested. The DXA and QUS capability to discriminate between ovariectomized and non-ovariectomized rats did not improve when tested together.